Reporting on environmental indicators - 2018

Fish

Mercury levels in fish from Laberge and Kusawa Lakes

Significance

Contaminants such as heavy metals can persist in the environment and can have serious health implications for wildlife and for people – especially those who depend on traditional foods. In Canada, mercury is a risk to Canadian ecosystems and human health (Environment and Climate Change Canada, 2016).

Most mercury in Yukon lakes and rivers comes from natural sources such as volcanoes, erosion and forest fires. Industrial sources and fuel burning can also release mercury that can travel to the north from industrial areas in the south through the movement of large air masses. Fish may absorb this mercury and pass it on to the humans who eat them (Environment and Climate Change Canada, 2016).

Climate change can influence mercury concentrations in some lakes. Yukon is experiencing increased runoff and precipitation, some from thawing permafrost. These changes influence how lakes naturally process mercury – either through adding mercury to the water or increasing food sources for the lake bacteria that process mercury (Chételat et al., 2015).

Profile

Nourishing Our Future: Building on the Kluane First Nation's Community Food Security and Strategy, Youth Engagement in Fisheries, and Fish Health in Kluane Lake

Lenita learns how to use a Direct Mercury Analyser. Photo credit: Western University.

Project significance

The overall goals of this project were: to promote the importance of consuming traditional foods; understand contaminant levels in fish from Kluane Lake; and provide base-line information for further monitoring efforts.

This project is a collaborative effort between the Kluane First Nation (KFN), Arctic Institute of Community Based Research (AICBR), University of Waterloo, Dan Keyi Renewable Resources Council (DKRRC), Kluane First Nation Traditional Territory area residents, Elders, and Youth. This multi-partner approach provided for a unique mix of scientific, community-based and Indigenous traditional knowledge collection.

The project assessed the nutrient values (omega-3 fatty acids, selenium, and zinc) as well as contaminant levels (mercury, organochlorine pesticides, and trace metals) in Lake Trout and Whitefish in Kluane Lake. Results from these assessments show that Kluane Lake fish are healthy and safe to eat. Compared to other lakes in Yukon, the Northwest Territories and Nunavut, concentrations of contaminants in Kluane fish are very low and the nutritional value of the fish is high.

Part of this research project included conducting interviews with Kluane First Nation citizens and traditional knowledge experts. The interviews solicited local observations of changes in quality, quantity and health of Kluane Lake fish, and whether there are concerns about contaminants in traditional foods. KFN youth involvement was essential throughout the project; three youth researchers traveled to the University of Waterloo and Western University (both in Ontario) to learn how to do contaminant and nutrient analysis in a research lab, analyzing fish from their own community.

Fish test results

None of the Lake Whitefish sampled exceed the Subsistence Consumption Guideline for mercury (0.2 ppm wet weight). Some of the larger Lake Trout (greater than 800 mm fork length) were found to have tissue mercury concentrations exceeding this guideline; however, the mean Lake Trout tissue mercury concentration (0.086 ± 0.091 ppm) did not. Larger trout (>~650 mm) are less likely to be consumed by the community (because smaller trout are considered tastier) and there are conservation measures on Kluane Lake that prohibit non-Aboriginal harvest of Lake Trout over 650 mm total length (Barker et al. 2014), reducing exposure to the higher levels of mercury in the larger Lake Trout. Mean tissue mercury concentrations in Kluane Lake Trout are significantly lower than mercury concentrations reported in other northern lakes (e.g. Lake Laberge and Kusawa Lake) (Stern et al. 2013).

Indigenous traditional knowledge results

Through the collection of community-based and indigenous traditional knowledge there was firm acknowledgement of the importance of fish as a dietary staple for Kluane First Nation (KFN) citizens and community members, historically, as well as in a modern-day context.

Many people have noticed changes in Kluane Lake fish, mostly related to climate change, and are becoming very concerned with the levels of contamination and pollution of the lake and its fish. Concerns surrounding climate change are: species decline, food security issues, warmer water temperatures, fluctuating water levels, and changing weather patterns.

Other changes observed were: where people are fishing, and the types of fish that are available. Changes in climate have affected harvesters’ access to traditional fishing spots. Fluctuating ice quality can make it unsafe to get to common fishing areas that were once accessible. The areas that people fish now have also changed due to shifting fish behaviors. With the warming temperatures, fish are changing spawning behaviors. People reported noteworthy changes to the fish in Kluane Lake including the taste and quality of the fish being consumed and the quantity and species found in specific areas.

Transportation modes, such as motorized boats and snowmobiles, and increased use of technology (such as fish finders) have also altered traditional harvesting methods. Fishing practices, including preparation and preservation techniques, differ from the past. Additionally, who fishes and how the fish are shared within a community has changed over time and circumstances.

Interviews with knowledge holders. Photo credit: Nelson Zabel.

Overall results

This project generated a renewed understanding, especially for youth, of the importance of long term stewardship and protection of the local fishery. The research outputs provide strong baseline data for future monitoring of fish health in Kluane Lake. It also provides reassurances to the Kluane First Nation, other area residents, and other fishers that Lake Trout and Lake Whitefish in Kluane Lake are nutritious and safe to eat.

What is happening?

Lake trout from Lake Laberge and Kusawa Lake, in southern Yukon, are monitored annually by the Northern Contaminants Program for mercury and other contaminants. The monitoring shows a correlation between fish length and mercury concentration, which is why consumption advisories are based on the length of the fish.

The average mercury level in lake trout flesh since monitoring started is 0.47± 0.21 µg/g for Lake Laberge (N=131) and 0.42 ± 0.34 µg/g for Kusawa Lake (N=135).

There is no clear trend over time in mercury concentrations in fish from these two lakes, and the length-adjusted concentrations fluctuate considerably from year to year (Figure 1 and 2).

These trends in mercury concentrations may be influenced by environmental factors such as temperature and precipitation as well as industrial mercury emissions in eastern Asia and global wind patterns.

Taking action

The Northern Contaminants Program works towards reducing and, where possible, eliminating contaminants in traditional/country foods, while providing information that assists individuals and communities make informed decisions about their food use.

Data quality

The Northern Contaminants Program has monitored fish for mercury and other contaminants since 1993 in lake trout from both Lake Laberge and Kusawa. This study is long-term, so annual sampling is projected well into the future. The data on mercury concentrations are adjusted for fish length to validly compare lakes and years. This accounts for differences in age among the fish.